U.S. patent application number 15/968804 was filed with the patent office on 2018-11-22 for optical element and optical connector.
This patent application is currently assigned to Konica Minolta, Inc.. The applicant listed for this patent is Konica Minolta, Inc.. Invention is credited to Kazuhiro Wada.
Application Number | 20180335579 15/968804 |
Document ID | / |
Family ID | 61827553 |
Filed Date | 2018-11-22 |
United States Patent
Application |
20180335579 |
Kind Code |
A1 |
Wada; Kazuhiro |
November 22, 2018 |
OPTICAL ELEMENT AND OPTICAL CONNECTOR
Abstract
An optical element connects to a ferrule that holds a plurality
of optical fibers. The optical element includes: a plurality of
lenses; and a cutout that engages with a projection part of the
ferrule. The lenses are positioned relative to the optical fibers
held in the ferrule by an engagement of the projection part and the
cutout.
Inventors: |
Wada; Kazuhiro; (Tokyo,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Konica Minolta, Inc. |
Tokyo |
|
JP |
|
|
Assignee: |
Konica Minolta, Inc.
Tokyo
JP
|
Family ID: |
61827553 |
Appl. No.: |
15/968804 |
Filed: |
May 2, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02B 6/3885 20130101;
G02B 6/3853 20130101; G02B 6/32 20130101; G02B 6/3865 20130101;
B29D 11/0075 20130101; G02B 6/3854 20130101 |
International
Class: |
G02B 6/38 20060101
G02B006/38 |
Foreign Application Data
Date |
Code |
Application Number |
May 17, 2017 |
JP |
2017-097972 |
Claims
1. An optical element that connects to a ferrule that holds a
plurality of optical fibers, comprising: a plurality of lenses; and
a cutout that engages with a projection part of the ferrule,
wherein the lenses are positioned relative to the optical fibers
held in the ferrule by an engagement of the projection part and the
cutout.
2. The optical element according to claim 1, wherein the cutout has
a width that becomes narrower from an open end to a back side of
the cutout.
3. The optical element according to claim 2, wherein the cutout has
a U shape, when viewed in an optical axis direction of the
lenses.
4. The optical element according to claim 2, wherein the cutout has
a semicircular shape, when viewed in an optical axis direction of
the lenses.
5. The optical element according to claim 1, wherein the projection
part of the ferrule is composed of two round shafts extending in
parallel, the cutout has two straight lines extending in a crossing
direction when viewed in an axis direction of the round shaft, in a
fabricated state of the optical element to the ferrule, the two
straight lines abut on circumferences of the round shaft, and
extended lines of the two straight lines cross at a position
located on a line segment that connects centers of the two round
shafts.
6. The optical element according to claim 5, wherein the two
straight lines form an open angle of 60.degree..+-.20.degree..
7. The optical element according to claim 5, wherein the cutout has
a V shape, when viewed in an optical axis direction of the
lenses.
8. The optical element according to claim 1, further including an
abut part that abuts the ferrule.
9. The optical element according to claim 1, wherein the optical
element is formed integrally by molding a glass.
10. The optical element according to claim 1, wherein the optical
element is formed integrally by molding a resin containing a glass
fiber.
11. The optical element according to claim 1, further including an
antireflection film formed at least on the lenses.
12. An optical connector comprising the optical element according
to claim 1, and a ferrule connected with the optical element.
Description
TECHNICAL FIELD
[0001] The following disclosure relates to an optical element and
optical a connector which are suitably used, for example, for
optical communications etc.
BACKGROUND ART
[0002] In various information/signal processing equipment including
a network apparatus such as a router, a server, and a host
computer, an information/signal processing is under a process of
large-scaling and improved in a speed. In these equipment, signals
have been conventionally transmitted by electric wirings between
CPUs and memories on circuit substrates (boards), between wiring
substrates, and between apparatuses (racks). However, such signal
transmission is not sufficient from viewpoints of a transmission
speed, a data transmission capacity, a power consumption, a radius
from a transmission path, and an interference of an electromagnetic
wave to the transmission path. In view of this, instead of above
mentioned electric wiring, so-called optical interconnection is
actually beginning to be introduced, which is excellent in the
above-mentioned viewpoints, and which transmits the signal by light
using an optical fiber etc. as the transmission path. In the
optical interconnection, an optical connector is conventionally
used to optically combine the optical fibers. The typical optical
connector has a lens which condenses the light emitted from an end
of one optical fiber to an end of other optical fiber.
[0003] In recent years, an amount of the optical communication
information rapidly increases, and a long-distance and a high-speed
transmission of the information are additionally desired. However,
a multimode fiber conventionally used adopts an optical fiber
having core diameters of 50 .mu.m and 62.5 .mu.m. As the multimode
fiber transmits a light signal in plural modes, there is a problem
of a shift between the attainment times of the signals, which
results in generation of a mode distribution. Thus, due to a data
loss caused by the mode distribution, the multimode fiber is
considered as unsuitable for the long-distance and high-speed
transmission.
[0004] On the other hand, a single mode fiber is an optical fiber
which has an extremely fine diameter of which mode field diameter
is about 9 .mu.m, and it has an advantage capable of suppressing
attenuation as much as possible by spreading a light signal in the
one mode. Accordingly, the single mode fiber has been often used,
which, unlike the transmission method using many modes such as the
multimode fiber, has the single attainment time of signal which,
thanks to no generation of a mode loss, is suitable for the
long-distance and high-speed transmission. However, in some cases,
the multimode fiber may still be used.
[0005] In the typical optical connector, multicores optical fiber
bodies composed of plural cores bundled are often joined, for the
purpose of increasing the information amount. The optical connector
used for such application typically has a holding member, and an
optical element. The holding member holds the multicores optical
fiber body which is called as a ferrule. The optical element is
arranged between a pair of ferrules and is composed of plural
lenses for spreading light effectively between plural core ends
held in the ferrule. Here, for the upmost suppression of the
transfer loss of the light signal, an optical axis of the lens is
coincided with the center of the optical fiber in high accuracy.
For this reason, a measure is important which improves a
manufacturing accuracy of the optical element with reduced
cost.
[0006] However, for provision of the optical element in high
accuracy and with low price, the manufacture technique using a
metallic molding can be selected. The typical metallic molding,
giving priority to the cost, often uses resin as a raw material. In
addition, if the technology of the patent documents 1 can be
diverted to create an optical element with resin containing the
glass fiber for example, an optical element can be provided of
which thermal expansion is less affected by change of an
environmental temperature. Alternatively, if the optical element is
molded from glass for example, it can exhibit the optical nature
stable for the change of environmental temperature.
CITATION LIST
Patent Literature
[0007] PTL 1: Japanese Patent Laid-open No. 2016-133518
SUMMARY OF THE INVENTION
[0008] When metallic molding the optical element, the subject
exists that how molds a positioning structure between the optical
element and the ferrule.
[0009] For example, a round shaft planted to the ferrule is fitted
into a fitting hole formed in the optical element. Such fitting
allows the optical axis of the lens to coincide with the center of
the optical fiber, without difficulty and in high accuracy.
However, metal molding the fitting hole which has a comparatively
long axis length for securing the fabricating accuracy is difficult
from an aspect of the molding technique. Furthermore, when the
optical element is molded by an injection molding, a weld line may
be formed near the fitting hole, which may reduce a positional
accuracy and environment-proof nature. On the other hand, a heat
and cool molding can also be performed for example as the measure
against the weld line, but it increases the cost. On the other
hand, the fitting hole can be formed on the molded product by a
machining, but it increases the number of processes thereby
increasing the cost.
[0010] Forming such fitting hole often becomes remarkable
especially when the optical element is molded using the glass.
[0011] One or more embodiments of the present invention provide an
optical element which can be fabricated in high accuracy and with
low price, as well as an optical connector using the optical
element.
[0012] An optical element reflecting one or more embodiments of the
present invention is connected to a ferrule to hold a plurality of
optical fibers, which includes a plurality of lenses, and at least
one cutout engaging with a projection part formed on the ferrule,
wherein the lens is positioned relative to the optical fiber held
in the ferrule by an engagement of the projection part and the
cutout.
[0013] According to one or more embodiments of the present
invention, the optical element which can be fabricated in high
accuracy and with low price, as well as the optical connector using
the optical element are provided.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 a perspective view of an optical connector according
to one or more embodiments.
[0015] FIG. 2 is an exploded view of the optical connector.
[0016] FIG. 3 is a sectional view of a pair of optical connectors
connected using a coupler, taken along a vertical plane passing a
line III-III, and viewed along arrow in FIG. 1.
[0017] FIG. 4A is a view showing a molding step of the lens plate
30 according to one or more embodiments.
[0018] FIG. 4B is a view showing a molding step of the lens plate
30 according to one or more embodiments.
[0019] FIG. 4C is a view showing a molding step of the lens plate
30 according to one or more embodiments.
[0020] FIG. 5 is a perspective view of a lower mold viewed from an
upper face according to one or more embodiments.
[0021] FIG. 6 is a front view of a lens plate 30' according to a
modification.
[0022] FIG. 7 is an exploded view of an optical connector according
to one or more embodiments.
[0023] FIG. 8 is a view of a lens plate 130 used for the optical
connector 120 according to one or more embodiments, viewed from
arrow VIII in FIG. 7.
[0024] FIG. 9 is a view of the lens plate 130 viewed from arrow IX
in FIG. 7.
[0025] FIG. 10A is a view showing a reheat molding step of the lens
plate 130.
[0026] FIG. 10B is a view showing a reheat molding step of the lens
plate 130.
[0027] FIG. 10C is a view showing a reheat molding step of the lens
plate 130.
DESCRIPTION OF THE EMBODIMENTS
[0028] Hereinafter, embodiments of the present invention will be
explained with referenced to drawing. FIG. 1 a perspective view of
an optical connector according to one or more embodiments. FIG. 2
is an exploded view of the optical connector. FIG. 3 is a sectional
view of a pair of optical connectors connected using a coupler,
taken along a vertical plane passing a line III-III, and viewed
along arrow in FIG. 1. A pair of optical connectors 20 are
connected by abutment and transmit a light signal between the
optical cables 10.
[0029] In FIG. 1, the optical connector 20 is composed of an
optical cable 10 having many cores (here, sixty cores) connected,
and it has a ferrule 21 and a lens plate 30 which is the optical
element. The ferrule 21 made of a thermosetting resin containing
the glass fibers is shaped into approximately a rectangular
parallelepiped, and it has an enlarged part 21a at an end where the
optical cable 10 is connected. The optical cable 10 has sixty
optical fibers 11 composed of cores and clads, and a covering part
12 protecting the optical fiber 11 (refer to FIG. 3).
[0030] As shown in FIG. 3, each enlarged part 21a is provided with,
at an inner part thereof, an end hole 21b to which the end of the
optical cable 10 is inserted. Plural penetration holes 21c are
formed to extend from a bottom of the end hole 21b in a
longitudinal direction of the ferrule 21, and the optical fibers 11
extended from an interior of the optical cable 10 are held in this
penetration hole 21c. The optical fiber 11 is for a single mode (or
for multimode), and as shown in FIG. 2, it has a tip exposed on an
end face 21d opposite to the enlarged part 21a.
[0031] In FIG. 2, circular openings 21e are formed at both sides in
the horizontal direction of a group of the penetration holes 21c
where the tips of the optical fibers 11 are exposed. Round shafts
(projection part) 22 are inserted in the circular openings 21e in
parallel each other, and each round shaft 22 has a tip projected
from the end face 21d.
[0032] In FIG. 2, the lens plate 30 of a rectangle plate shape has
a rectangular concave parts 30a recessed in centers of a front face
and a back face, and an abut face 30b formed around the concave
part 30a. In each concave part 30a, lens faces 30c are formed with
five lines and twelve rows arrangement, and the opposing lens faces
30c on the front face and back face have biconvex shapes of which
optical axes are coincided to constitute the lens. A cutout having
a U shape, when viewed in the optical axis direction, is formed on
the lens plate 30 in the middle of respective both sides. The
cutout 30d has an upper wall 30e and a lower wall 30f extending in
parallel toward the concave part 30a, and a half cylinder face 30g
connecting the upper wall 30e and the lower wall 30f. An inner
diameter of the half cylinder faces 30g is selected equal to an
outer diameter of the round shaft 22.
[0033] An antireflection film is formed in each concave part 30a
located in the centers of the front face and the back face of the
lens plate 30, and a part of the abut face 30b located therearound.
The antireflection film provided in such area brings about an
advantage, that is, even if the antireflection film is peeled, its
progress stops at the edge position of the concave part 30a and is
prevented from influencing to the lens face 30c. However, the
antireflection film can be formed avoiding the cutout 31d. This is
because the antireflection film, formed on the cutout 30d during
insertion of the round shaft 22 thereinto, may be peeled off and
worsen a positional accuracy.
[0034] Next, molding steps of the lens plate 30 will be explained.
FIG. 4 shows the molding step of the lens plate 30, with omitting
lens and lens transferring face. FIG. 5 is a perspective view
showing the lower mold from the upper face. In FIG. 4 (a), an upper
mold MD1 has an optical face transferring face MD1a corresponding
to one concave part 30a and one lens face 30c. On the other hand,
as shown in FIG. 5, a lower mold MD2 has an optical face
transferring face MD2a corresponding to other concave part 30a and
other lens face 30c, and a cutout molding face MD2b corresponding
to the cutout 30d. The optical face transferring face MD2a and the
cutout molding face MD2b are simultaneously formed by machining on
the single lower mold MD2, so that the positional relation between
the lens face 30c and the cutout 30d to be transferred and molded
by these faces is determined in high accuracy.
[0035] As shown in FIG. 4 (a), with opposing the optical face
transferring faces MD1a and MD2a as shown in FIG. 4 (b), the upper
mold MD1 is made to approach to the lower mold MD2 to clamp the
both molds.
[0036] A cavity CV is formed between the lower mold MD2 and the
upper mold MD1 clamped. A resin containing a melted glass fiber is
filled into this cavity CV from a gate (not shown) and then
solidified. During solidification, the cutout molding face MD2b can
transfer and mold the cutout in high accuracy.
[0037] Then, as shown in FIG. 4 (c), with spanning the lower mold
MD2 from the upper mold MD1, the lens plate 30 (refer to FIG. 2),
in which the concave part 30a having the lens face 30c and the abut
face 30b are molded, is demolded from the both molds. Here, thanks
to the excellent demolding nature of the cutout molding face MD2b,
the lens plate 30 can be demolded easily, without damaging cutout
30d. Then, an antireflection film is formed in a successive process
by a vapor depositing method etc. with masking a circumference of
the lens plate 30 including the cutout 30d. The vapor depositing
method is omitted in explanation because of its publicity.
[0038] Next, a fabrication mode and a joining mode of the optical
connector 20 will be explained. Here, as shown in FIG. 2, it is
presumed that the end of the optical cable 10 is connected to an
end hole 21b of the ferrule 21, and the tip of the optical fiber 11
is exposed on the end face 21d. During fabrication of the optical
connector 20, the round shafts 22 are inserted into the circular
openings 21e of the ferrule 21, and the protruded end of the round
shaft 22 is made to contact with the half cylindrical face 30g of
the cutout 30d of the lens plate 30. In this state, one abut face
30b is made to abut end face 21d of the ferrule 21. Here, thanks to
each lens face 30c formed in the concave part 30a, the lens face
peaks are no danger of interfering with the end face 21d, which
results in a predetermined clearance secured therebetween.
Furthermore, each lens face 30c is positioned in high accuracy
using the middle point between two lines each of which passes
through the center of half cylinder faces 30g of a pair of cutout
30d as the standard. Furthermore, the end of the optical fiber 11
held in the penetration hole 21c is also positioned in high
accuracy using the middle point between two central lines of a pair
of circular openings 21e as a standard. Accordingly, the optical
axis of each lens face 30c and an end center of the optical fiber
11 opposed thereto can be coincided in high accuracy. Meanwhile,
the interval between a pair of half cylinder faces 30g can be
slightly expanded relative to the interval between the two round
shafts 22, which allows the round shafts 22 to elastically deform
slightly, when the round shafts 22 engage with the half cylinder
faces 30g. Here, so-called pull-out force, that is the force
necessary to pull out (or push) the lens plate 30 from(into) the
round shafts 22, can be set to a predetermined value utilizing face
pressures acting between the round shafts 22 and the half cylinder
faces 30g.
[0039] Furthermore, when joining the optical connectors 20,
couplers 41 and 42 shown in FIG. 3 are used. The couplers 41 and 42
are respectively made into an enclosure shape which has one opened
end. The couplers 41 and 42 have flange parts 41a and 42a at side
of the opened end, and closed ends 41b and 42b provided with
derivation holes 41c and 42c at side opposite to the opened end. An
engaging concave part 41d is formed on an opposing end face of the
flange part 41a, and an engaging convex part 42d is formed on an
opposing end face of the flange part 42a, corresponding to the
engage concave part 41d.
[0040] As shown in FIG. 3, with housing the ferrules 21 inside the
couplers 41 and 42 respectively, the optical cables 10 are pulled
out externally through the derivation holes 41c and 42c. During
pull-out, the enlarged parts 21a of the ferrules 21 engage with
inner circumference walls of the closed ends 41b and 42b to
position the ferrules 21 relative to the couplers 41 and 42. In
this state, the lens plates 30 are exposed on the opening ends of
the couplers 41 and 42.
[0041] When engaging the convex part 42d of the flange part 42a is
engaged with the concave part 41d of the flange part 41a to closely
attach the flange parts 41a and 42a, the abut faces 30b of the
opposing lens plates 30 are abutted mutually. During abutment,
thanks to each lens face 30 formed in the concave part 30a, there
is no danger of mutual interfere of the lens face peaks, which
results in a predetermined clearance secured therebetween. The
engagement of the engage concave part 41d and the engage convex
part 42d allows the optical axes of the opposing lens faces 30c to
coincide in high accuracy. Thus, a pair of optical connectors 20
are joined in high accuracy through the couplers 41 and 42. A
clearance between the circular opening 21e of the ferrule 21 and
the round shaft 22 is selected to be equal to or smaller than a
clearance between the round shaft 22 and the cutout 30d of the lens
plate 30. Furthermore, a clearance between the round shaft 22 and
the cutout 30d is selected to be smaller than a clearance of an
area where the couplers 41 and 42 and the optical cables 10 are
mutually engaged. These dimensional relations are not illustrated
clearly.
[0042] In FIG. 3, light (for example, having a wavelength of 850
nm, 1310 nm, and 1550 nm) spreads in the optical fibers 11 of one
optical cable 10. Then, light is emitted from the end of the
ferrule 21, and makes incident into one lens plate 30 in a state of
emission light, and is emitted from one lens plate 30 as a
collimate light. The emitted collimate light makes incident into
the other lens plate 30, and is emitted from the other lens plate
30 as a convergence light. This convergence light condenses at the
end of the optical fiber 11 of the other ferrule 21, and is
transmitted therefrom through the other optical cable 10. A
diameter of the collimate light is expanded to about five times of
a core diameter of the single mode optical fiber 11. Thus, even if
optical axes are shifted between a pair of lens plates 30, the
influence resulted from such shift can be inhibited.
[0043] According to one or more embodiments, the lens plates 30 are
metallic molded from the resin containing the glass fibers, which
are joined to the ferrules 21 by engaging their cutouts 30d to the
round shafts 22. Thus, the lens faces 30c and the optical fibers 11
can be positioned in high accuracy. Meanwhile, the lens plates 30
may be molded of the resin not containing the glass fiber.
[0044] FIG. 6 is a front view of a lens plate 30' according to a
modification of one or more embodiments, which shows the lens plate
30' in an engaged state with the round shaft 22. In this
modification, as the cutout 30d' is made into a half cylinder
shape, that is, as shown in FIG. 6, the cutout 30d' has a
semicircular shape, when viewed in the optical axis direction of
the lens face 30c. The other structure in the modification is the
same as the structure of the one or more embodiments mentioned
above.
[0045] FIG. 7 is an exploded view of an optical connector according
to one or more embodiments. FIG. 8 is a view of a lens plate 130
used for the optical connector 120 according to one or more
embodiments, viewed from arrow VIII in FIG. 7. FIG. 9 is a view of
the lens plate 130 viewed from arrow IX in FIG. 7. In one or more
embodiments, an optical cable 10, a ferrule 21, and a round shaft
22 are the same as those used in the one or more embodiments
mentioned above. On the other hand, the optical cable 10 has
twenty-four cores structure, and the penetration holes 21c of the
ferrule 21 have two lines and twelve rows arrangement corresponding
to the above structure.
[0046] A lens plate 130 is made of a glass mold and has a plate
shape. The lens plate 130 has a thin plate part 130a, abut parts
130b, and cutouts 130d. The thin plate part 130a has a plate
thickness .DELTA.1 (FIG. 9) and includes faces in each of which a
lens surface 130c is arranged in an array of two lines and twenty
rows. Each abut part 130b is overhung by an overhang amount
.DELTA.2 (FIG. 9) from the thin plate part 130a toward the both
sides in the optical axis direction. Each cutout 130d having a V
shape is formed on each side face of the thin plate part.
[0047] In FIG. 8, each cutout 130d has two planes 130e and 130f,
and a curved face 130g connecting the planes 130e and 130f. In
other words, the cutout 130d has two straight lines extending in a
crossing direction, when viewed in the axis direction of the round
shaft 22. The planes 130e and 130f can be disposed in an open angle
.theta. of 60.degree..+-.20.degree.. Considering inferiority of
glass to resin in a molding nature, the lens plate 130 is formed
with the cutouts, instead of the holes, to relieve a burden during
molding, which contributes to the cost reduction. However, the lens
plate 130 may be formed from resin. As shown in FIG. 9, the lens
plate 130 has a symmetrical shape about a central face in the
thickness direction.
[0048] Next, molding steps of the lens plate 130 will be explained.
FIG. 10 shows a reheat molding step of the lens plate 130. In FIG.
10 (a), an upper mold MD3 has an optical face transferring face
MD3a corresponding to one lens face 130c, and an abut part molding
face MD3b molding one abut part 130b. On the other hand, a lower
mold MD4 has an optical face transferring face MD4a corresponding
to other lens face 130c, an abut part molding face MD4b molding
other abut part 130b, and a cutout molding face MD4c corresponding
to the V-shaped cutout. The optical face transferring face MD4a and
the cutout molding face MD4c are simultaneously formed on the
single lower mold MD4 by machining, so that the positional relation
between the lens face 130c and the cutout 130d, which are
transferred and molded by the above faces, is determined in high
accuracy.
[0049] As shown in FIG. 10 (a), the optical face transferring faces
MD3a and MD4a opposes with intervening a preform PF of glass
therebetween. As shown in FIG. 10 (b), during heating the upper
mold MD3 and the lower mold MD4, the upper mold MD3 approaches to
the lower mold MD4 for clamping the both molds, then the preform PF
of glass is cooled for its solidification.
[0050] Then, the upper mold MD3 is spanned from the lower mold MD4.
Thus, as shown in FIG. 10 (c), the lens plate 130 formed with the
lens face 130c and the cutout 130d can be demolded from both molds.
Meanwhile, in one or more embodiments, the antireflection film may
be formed on the face of the thin plate part 130a including the
lens face 130c, which can suppress the loss during
communication.
[0051] Next, a fabrication mode and a joining mode of the optical
connector 120 will be explained. Here, as shown in FIG. 7, it is
presumed that the end of the optical cable 10 is connected to an
end hole 21b of the ferrule 21, and the tip of the optical fiber 11
is exposed on the end face 21d.
[0052] During fabrication of the optical connector 20, the round
shafts 22 are inserted into the circular openings 21e of the
ferrule 21, and the protruded end of the round shaft 22 is made to
contact with the cutout 130d of the lens plate 130.
[0053] Specifically, in FIG. 8, a right half outer circumference
face of the left round shaft 22 contacts with the plane 130e of the
cutout 130d at a point P1, and contacts with planes 130f at a point
P2. On the other hand, a left half outer-circumference face of the
right round shaft 22 contacts with the plane 130e at a point P3,
and contacts with the planes 130f at a point P4. When viewed in the
axis direction of the round shaft 22 in fabricated state of the
lens plate 130 and the ferrule 21, two straight lines (lines
representing the planes 130e and 130f) contact with the outer
circumference of the round shaft 22. A crossing point of the
extension lines (shown by dotted lines in FIG. 8) of two straight
lines are located on a line segment connecting the two centers of
the two round shafts 22. Thus, the lens plate 130 is positioned in
high accuracy relative to the round shafts 22.
[0054] Further, each lens face 130c is positioned in high accuracy
using the middle point between the center lines of a pair of cutout
130d as the standard. Furthermore, the end of the optical fiber 11
held in the penetration hole 21c is also positioned in high
accuracy using the middle point between two central lines of a pair
of circular openings 21e as a standard. Accordingly, the optical
axis of each lens face 30c and the end center of the optical fiber
11 opposed thereto can be coincided in high accuracy.
[0055] Meanwhile, the bearing pressure between the cutout 130d and
the round shaft 22 changes by adjusting the interval between the
points P1 and P3, and the interval between the points P2 and P4.
The change of bearing pressure allows to set the pull-out force of
the lens plate 130 during pull-out (or pushing) from (into) the
round shaft 22 to set in a predetermined value.
[0056] Furthermore, each face of the thin plate part 130a formed
with each lens face 130c is positioned at the distance .DELTA.2
(refer to FIG. 9) from each face of the abut part 130b. Therefore,
the lens face peaks are no danger of interfering with the end face
21d of the ferrule 21, which results in predetermined clearance
secured therebetween.
[0057] Furthermore, joining the optical connector 120 can use
couplers which are the same as the couplers 41 and 42 shown in FIG.
3. If the flange parts of the couplers 41 and 42 which respectively
house the optical connector 120 are closely attached, the abut
parts 130b of the opposing lens plates 130 are mutually abutted.
Here, each face of the thin plate part 130a formed with each lens
face 130c is positioned at the distance .DELTA.2 (refer to FIG. 9)
from each face of the abut part 130b. Therefore, there is no danger
of mutual interfering of the lens face peaks, which results in a
predetermined clearance secured therebetween. The other structure
of one or more embodiments is the same as those of the one or more
embodiments mentioned above.
[0058] The present invention is not limited to the embodiments
described in the specification but includes other embodiments and
modifications. This is apparent to the person skilled in this field
from the embodiments and the technical concept described in this
specification. For example, the optical connector according to this
embodiment can combine the single mode optical fibers or the
multimode optical fibers. Furthermore, the projection part does not
necessarily need to be the round shaft. Furthermore, the cutout of
the lens plate may have shapes other than the V shape, the U shape,
and the semicircular shape, as long as a width of the cutout
becomes narrower as it goes from the open end to a back side.
[0059] Although the disclosure has been described with respect to
only a limited number of embodiments, those skilled in the art,
having benefit of this disclosure, will appreciate that various
other embodiments may be devised without departing from the scope
of the present invention. Accordingly, the scope of the invention
should be limited only by the attached claims.
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